 sudo mkdir -p /opt/gcc 
cd /opt/gcc
sudo wget http://ftp.gnu.org/gnu/gcc/gcc-5.5.0/gcc-5.5.0.tar.gz
tar –xvf gcc-5.5.0.tar.gz
cd gcc-5.5.0
sudo ./contrib/download_prerequisites
sudo ./configure --prefix=/usr/local/gcc --enable-bootstrap  --enable-checking=release --enable-languages=c,c++ --disable-multilib
sudo make -j 8 &&sudo  make install